Nature Vs. Nurture Essay Example

view; it is not primarily our environment and the genetic structure that are responsible for our behaviour it is both.

Twins are a valuable source of observation because their genotypes and family environments tend to be similar. Behavioural geneticist break down the vast term “environment” into two parts, shared and non-shared. The shared environment is what twins or other siblings have in common; their neighbourhood, church, social status and the child-raising techniques. The non-shared environment is whatever those siblings do on their own time (Turkheimer & Waldron, 2000). Monozygotic (MZ) more commonly known as “identical” twins share nearly 100% of the same genes and are therefore very helpful when looking at the nature side of the debate.

Dizygotic (DZ) or “fraternal” twins share only 50% of the same genes and are no more similar than two siblings born after separate pregnancies (Bouchard, 1999). Fraternal twin studies are helpful to study because they tend to share many aspects of their environment. Due to the fact that they are born at the same time and place, they often share the same environment, culture, community and parenting style Twin studies provide support for researchers to separate the environmental and genetic influences on individual traits and behaviours.

An example of a twin study is a study conducted by Koeppen-Schomerus, Stevenson and Plomin (2001). The aims of this study was to test a large sample of 4 year old twins to see if there was a bigger connection between genetics or environment in developing asthma. The sample consisted of 4910 twin pairs: 1658 monozygotic (MZ), 1651 dizygotic same sex (DZss), and 1601 dizygotic opposite sex (DZos) who

were born in England and Wales in 1994 and 1995. Data on asthma status were obtained from the twin’s parents by postal questionnaire.

The result where that when developing asthma they estimated it to 68% heritability, 13% shared environment and 19% non-shared environment. These findings indicate that asthma is highly heritable (Koeppen-Schomerus, Stevenson, Plomin, 2001). This study shows that by using twin studies we can test in some way and retrieve scientific prove when discussing if it is nature or nurture that makes us who we are. This particular study shows that genetics have an important role in human development. Researchers use adoption studies to determine the contributions of genetic and environmental factors (Cadoret, 1995).

Adoption studies provide important information about the significance of specific genetic and environmental factors in human behaviour. The studies are important to evaluate the interactions of genetic and environmental factors in providing information about human characteristics such as intelligence (IQ) and disorders, such as alcoholism (Cadoret, 1995). By separating the child from its biological parents and placing them in a new environment gives a distinct separation between genetics and environmental influences on the child’s development (Rutter 1999).

Hence the studies of this child will have the environmental influences from their adoptive parents and the genetics influences from their birth parents. One of the first large adoption studies was the Heston Study in 1966. Heston identified 47 adopted children whose biological mothers had schizophrenia. The report compared these children to a group of children from the same foster homes whose biological mothers did not have schizophrenia. The study found that 16. 6-precent of the children of schizophrenic mothers

became schizophrenic as adults, compared to none of the control children (Heston, 1996).

This means that even though the schizophrenic parents did not raise any of the children, the children who had schizophrenia in their biological families where far more likely to develop the disorder. Another study shows that parents giving up their children for adoption have higher rats of antisocial behaviour and antisocial personality hence the child may have low inhibition (low threshold for arousal) increasing the risk of some children behaving antisocially (Howe, 1998).

A famous study about adoption is a study conducted by Scarr and Weinberg (1976), this study supports the importance of environment on IQ. In the 1976 adoption study, 130 African American and interracial children adopted at an average age of 18 months by socially advantaged white families in Minnesota scored and average of 106 on the Binet or Wechsler IQ test. That was about 15 points higher than the typical IQ earned by African American children from the North Central region of the United States (Scarr & Weinberg, 1976). These findings show the powerful role that environment plays on IQ.

Adoption studies are important because they include two sets of factors that may account for differences in behaviour, personality: biological parents and environmental parents. Usually any links between the biological parents and the child that is given away is usually explained by genetics, and any links between the adoptive, or environmental parents, to the adopted child is usually attributed to environment (Plomin, 1997). Adoption and twin studies have influenced the nature versus nurture debate by providing scientific support that both genes and environment influences a human

being.

It gives scientist opportunities to see how different environments can have a huge impact on human development as well as genetics. By removing a child from their genetic environment and putting them in a new and different home will show how genetics still impacts a persons life and disorders. In twins this has been shown through different twin studies (when twins have been separated by birth) that they share some of the same characteristics even though they have been raised in different environments and have had different parental influence.

There is often a clear difference between fraternal twins, seeing as school, community and the social network around them also influences them and therefor they grow up as to individuals. It is what happens to us as individuals, it is the life we choose for ourselves. When looking at adoption studies there is a bigger environmental factor, seeing as their adoptive parents and the surroundings they choose for them are influencing the child or adolescent.

The nature versus nurture debate is a long and continuously ongoing debate. It is not easy to say whether it is the nature side or the nurture side that plays the bigger role. What we do know is that it has been conducted studies and findings that provide valid information about both sides of the debate, but so far there has been no evidence supporting that it is either the nature or the nurture side of the debate that has influenced human development the most.